1. Field of the Invention
This invention relates in general to subsea wellhead assemblies, and in particular to a full bore wellhead housing, wherein the operator sets a casing hanger load shoulder ring during the casing hanger running procedure.
2. Background of the Invention
A typical subsea well has a wellhead housing at the upper end of the well. The wellhead housing is a tubular member having a bore. A string of large diameter casing attaches to the lower end of the wellhead housing and extends into the well. After further drilling through the wellhead housing, a smaller diameter string of casing is installed. A casing hanger at the upper end of the smaller diameter string of casing lands in the bore on a load shoulder.
In one type of wellhead housing, the load shoulder is permanently formed in the bore during manufacturing. This permanent load shoulder reduces the diameter of the bore below the load shoulder. In some instances, a full diameter is desired for the entire length of the bore. It has been proposed to install a split load ring in the bore before running the first casing hanger to provide a load shoulder. However, running the load ring on a running tool would require an extra trip from the drilling rig to the sea floor. In very deep water, the extra trip would be expensive.
In another technique, a split load ring is secured in a contracted diameter position to the casing hanger. When the casing hanger enters the bore, the load ring moves to a set position on a support shoulder provided in the bore.